Manufacturing method for two-dimensional image detectors and two-dimensional image detectors

ABSTRACT

A TFT array is formed on a glass substrate (step P 1 ). A surface protection layer is formed on the glass substrate so as to cover the TFT array (step P 2 ). The glass substrate is divided to form active matrix, substrates with the surface protection layer being provided (step P 3 ). The divided active matrix substrate is chamfered along its edges (step P 4 ). The surface protection layer is removed from the active matrix substrate (step P 5 ). An X-ray conductive layer is formed on the TFT array where the surface protection layer has been removed (step P 6 ). By these steps, pollutants produced during the division and chamfering of the glass substrate are prevented from polluting the TFT array and the X-ray conductive layer, and the active element array and the semiconductor layer is prevented from deteriorating in terms of performance in manufacturing process for a two-dimensional image detector.

This application is a continuation of U.S. patent application Ser. No.09/657,528, now U.S. Pat. No. 6,559,451 filed Sep. 8, 2000, the entirecontent of which is hereby incorporated by reference in thisapplication.

FIELD OF THE INVENTION

The present invention relates to manufacturing methods fortwo-dimensional image detectors capable of detecting images by means ofX-rays and other kind of radiation and visible, infrared, and other kindof light and also relates to those two-dimensional image detectors.

BACKGROUND OF THE INVENTION

Conventionally known radiation two-dimensional image detectors(hereinafter, will be referred to simply as two-dimensional imagedetectors) include semiconductor sensors arranged in rows and columnswith a switching element provided to each of the sensors. Thesemiconductor sensor generates electric charges (electron-hole pairs)upon detection of X-rays or other radiation (hereinafter, will be simplyreferred to as radiation). In the two-dimensional image detector, allthe switching elements in a row are turned on to read electric chargesfrom the semiconductor sensor in each column. The reading operation isperformed for each column to detect a two-dimensional image.

The structure and principles of the two-dimensional image detector areexplained in specific terms in publications including L. S. Jeromin, etal., “Application of a-Si Active-Matrix Technology in a X-Ray DetectorPanel”, SID 97 DIGEST, pp. 91-94, 1997; and Japanese Laid-Open PatentApplication No. 6-342098/1994 (Tokukaihe 6-342098; published on 13December 1994).

Now, the structure and principles of the conventional two-dimensionalimage detector will be discussed in reference to FIGS. 17 and 13. WhilstFIG. 17 is a perspective view schematically showing a structure of thetwo-dimensional image detector, FIG. 18 is a cross-sectional viewshowing a structure of a pixel shown in FIG. 17.

The two-dimensional image detector includes an active matrix substrate100, a photoconductive film 112, a dielectric layer 114, an upperelectrode 116, a high voltage source 118, and an amplifier 120.

The active matrix substrate 100 is constituted by a glass substrate 102,electrode wires (gate electrode line 104 a and data electrode line 104b) 104 arranged in an XY matrix (arranged in rows and columns) on theglass substrate 102, thin film transistors (hereinafter, will bereferred to as TFTs) 106 connected to the electrode wires 104, electriccharge storage capacitances 108 connected to the TFTs 106, etc.

The active matrix substrate 100 may be one of those used in manufactureof liquid crystal displays. An active matrix substrate used in an activematrix liquid crystal display (AMLCD) includes, among other components,TFTs 106 formed from amorphous silicon (a-Si) or polysilicon (p-Si),electrode wires 104, and electric charge storage capacitances 108, andcan be used in the two-dimensional image detector with few modificationsin design.

The photoconductive film 112, the dielectric layer 114, and the upperelectrode 116 are formed so as to cover a substantial entirety of theactive matrix substrate 100.

The photoconductive film 112 is composed of a semiconductor materialthat produces electric charges (electrons-holes) when exposed toradiation. In the documents cited above, amorphous selenium(hereinafter, will be referred to as a-Se) is employed for use as thephotoconductive film 112, since aide material has high dark resistance,exhibits satisfactory photoelectricity when exposed to radiation(X-rays), and is easy to form large films by vapor deposition.Specifically, a-Se is deposited 300 μm to 600 μm thick by vacuum vapordeposition to form the photoconductive film 112.

Now, the operation principles of the two-dimensional image detector willbe discussed.

When the photoconductive film 112 composed of a-Se is exposed toradiation, electric charges (electrons-holes) develop in thephotoconductive film 112. As shown in FIGS. 17 and 18, the upperelectrode 116 is electrically connected in series with Cs electrodes 108a in the electric charge storage capacitances 108. Upon application ofvoltage across the upper electrode 116 and the Cs electrodes 108 a,those electrons and holes developing in the photoconductive film 112move toward the anodes and cathodes, building up electric charges in theelectric charge storage capacitances 108.

The electric charges thus accumulated in the electric charge storagecapacitance 108 are sent to the amplifier 120 through the data electrodeline 104 b by changing the TFT 106 into an on-state by means of an inputsignal from the gate electrode line 104 a. Since the electrode wires 104(the gate electrode lines 104 a and the data electrode lines 104 b), theTFTs 106, and the electric charge storage capacitances 108 are arrangedto form an XY matrix as explained earlier, information on atwo-dimensional radiation image is obtainable by sending an input signalsequentially to the gate electrode lines 104 a.

If the photoconductive film 1 exhibits photoconductivity to visible orinfrared light, as well as in radiation, the two-dimensional imagedetector can function as a two-dimensional visible or infrared imagedetector. For example, an a-Se film mentioned above exhibits asatisfactory level of photoconductivity to visible light and avalancheeffect on the application of a strong electric field. Studies are underway to develop supersensitive image sensors (two-dimensional imagedetectors) by means of the avalanche effect

In manufacture of the two-dimensional image detector, the threeprocesses A to C below are indispensable following the fabrication soactive matrix elements (including the TFTs 106 and the electric chargestorage capacitances 108).

A. A-Se Film Deposition Process

In this process, an a-Se film is deposited by means of vacuum vapordeposition on the active matrix substrate 100 so as to cover at leastareas in which the active matrix elements are formed.

B. Glass Cutting Process

In this process, a piece of mother glass is cut into the active matrixsubstrate 100 by a scribe or dicing technology.

Here, mother glass refers to the base material of the piece of glass onwhich active matrix elements are fabricated. Dividing a piece of motherglass into a designated dimensions will form active matrix substrates100.

Further, in this process, after active matrix substrates 100 are cutout, the edges along which the active matrix substrate 100 has been cutout are subjected to a chamfering process as necessary.

The glass cutting process is performed after the fabrication of matrixelements for the following reasons. First, the production line foractive matrix substrates 100 includes dedicated machines exclusivelyused for a particular substrate size. Accordingly, the piece of motherglass, after having been subjected to the process to fabricate activematrix elements, needs to be of a size suitable to those dedicatedmachines. The piece of mother glass thus processed is then divided intosmaller pieces of a required size for use as two-dimensional imagedetectors.

The second reason is that it is difficult in the fabrication process ofactive matrix elements to fabricate normal active matrix elements nearthe periphery of a glass substrate. This is chiefly due to thedifficulty to satisfy suitable conditions for the fabrication of activematrix elements near the periphery of a glass substrate and the handlingassembly directly contacting the periphery of the glass substrate.Therefore, the piece of mother glass needs to be of a size that actuallyforms the two-dimensional image detectors, plus the periphery. Theunnecessary periphery is cut off after the fabrication of active matrixelements.

C. Mounting Process

In this process, various components and circuitry are mounted on theactive matrix substrate 100 so as to obtain electric charges and otherinformation from the active matrix substrate 100.

However, regarding a two-dimensional image detector with an a-Se filmdeposited covering a substantial entirety of the active matrix substrate100, she following problems occur in its manufacturing process.

It is known that if pollutants in water, air, and the like stick to atypical a-Se film after its deposition, it is likely to change itsproperties, e.g., crystalize, starring where those foreign objectsstick.

Therefore, if an a-Se Film deposition process is followed by a glasscutting process and a mounting process, foreign objects, such as glassparticles formed during the cutting process, processing water used fordicing and chamfering, and dust developing during the mounting process,touch the a-Se film and causes deterioration of properties of the a-Sefilm.

Meanwhile, if a glass cutting process and a mounting process arefollowed by an a-Se film deposition process, the surface of the activematrix substrates 100 is polluted with the glass particles, processingwater, and dust.

Especially, glass particles are hazardous in its possibility ofscratching the active matrix elements. They are even so, if they aresmall and stick to the surface of the active matrix substrate 100,because it is very difficult to remove them with supersonic wave oranother similar cleaning technique. In addition, the TFTs 106, formingpart of the active matrix element, are very sensitive to pollution. Ifan a-Se film is deposited on a polluted active matrix element, the a-Sefilm also becomes polluted, which causes deterioration of properties inboth the a-Se film and the active matrix element.

Even after the two-dimensional image detector is completelymanufactured, dew drops may develop inside the two-dimensional imagedetector depending on the environment, causing deterioration inproperties of the a-Se film.

In the two-dimensional image detector, an electric field approximatelyas high as 10V/μm needs to be applied to the photoconductive film 112 toimprove the efficiency in collecting electric charges. For this purpose,a voltage from coupe of thousands to ten thousands volts is applied tothe upper electrode 116. Therefore, electric discharge is likely in thevicinity of the upper electrode 116, destructing elements ordeteriorating their properties.

SUMMARY OF THE INVENTION

The present invention has an object to prevent deterioration inperformance of the a-Se film (semiconductor layer) and the active matrixsubstrate. For this purpose, methods of manufacturing a two-dimensionalimage detector are presented whereby the a-Se film and the active matrixsubstrate are not polluted in the manufacturing process. Also,arrangements of two-dimensional image detectors are presented that canresolve problems in use environments, typically represented by dew dropsand electric discharge in the two-dimensional image detector, and thatoffers a satisfactory level of insusceptibility to environmentalconditions.

To achieve the object, a method of manufacturing a two-dimensional imagedetector in accordance with the present invention is a method ofmanufacturing a two-dimensional image detector including:

a semiconductor layer for producing electric charges according toincident electromagnetic waves; and

a substrate having an active element array for reading out the electriccharges produced by the semiconductor layer,

the manufacturing method comprising the steps of:

(1) forming the active element array on the substrate;

(2) forming a protection member on the substrate so as to cover an areain which the active element array is formed;

(3) dividing into smaller pieces the substrate on which he protectionmember is already formed;

(4) removing the protection member from the divided pieces; and

(5) forming the semiconductor layer on the active element array wherethe protection member is removed.

According to the method, an active element array is formed on asubstrate, and then a protection member is formed on the active elementarray. Subsequently, the substrates divided. After removing theprotection member, a semiconductor layer is formed on a surface of theactive element array which was protected by the protection member.

As mentioned above, depending on the production line to fabricatesubstrates (active matrix substrates) with an active element array,sometimes it becomes necessary to divide the substrate into activematrix substrates of a preferred size after the formation of the activeelement array on the substrate. When the substrate is divided, thesubstrate comes in contact with materials that can scratch or pollutethe active element array (hereinafter, will be collectively referred toas pollutants), such as glass particles and processing water. The samephenomenon happens when the substrate is divided and the divisions arechamfered.

By contrast, in the method, the active element array is covered with aprotection member when the substrate is divided. This preventspollutants produced in the division of the substrate from directlycontacting the active element array.

As a result, the active element array can be kept clean and free fromscratches, and the deterioration in performance of the active elementarray can be prevented. As a result, according to the method, activematrix substrates are manufactured with the active element arrayoperating reliably and stably. In addition, the production yields of theactive matrix substrates improve.

Besides, the semiconductor layer for converting electromagnetic wavesinformation into electric charges information can be formed on thesurface of the active element array that is clean because being exposedby removing the protection member only after dividing the substrate.Therefore, the semiconductor layer can be prevented from contactingpollutants produced in the division of the substrate. Thus, according tothe method, the semiconductor layer can be prevented from deterioratingin terms of performance and reliability improves, even when thesemiconductor layer is constituted by an a-Se film or other materialsthat are highly sensitive to pollutants.

As a result, highly reliable two-dimensional image detector can bemanufactured with the active element array and the semiconductor layerexhibiting a satisfactory level of performance.

Another method of manufacturing a two-dimensional image detector inaccordance with the present invention is a method of manufacturing atwo-dimensional image detector including:

a semiconductor layer for producing electric charges according toincident electromagnetic waves; and

a substrate having an active element array for reading out the electriccharges produced by the semiconductor layer,

the manufacturing method preferably comprising the steps of:

(1) forming the active element array on the substrate;

(2) forming the semiconductor layer on the active element array;

(3) forming a protection member on the substrate so as to cover an areain which the semiconductor layer is formed; and

(4) dividing the substrate on which the protection member is alreadyformed.

According to the method, an active element array formed on a substrate,and topped by a semiconductor layer. Then a protection member is formedto cover an area in which the semiconductor layer formed, followed bythe division of the substrate.

In the method, the semiconductor layer can be formed on the activeelement array after the step of forming the active element array, butbefore any step that produces pollutants.

Therefore, the active element array can be prevented from pollution, andthe semiconductor layer can be formed on a clean surface.

Further, according to the method, the substrate is divided with theprotection member being provided to cover the area in which thesemiconductor layer is formed; therefore, the semiconductor layer can beprevented from being polluted by the aforementioned pollutants duringthe division of the substrate.

Furthermore, in the method, the step of removing the protection membercan be omitted. This reduces the number of steps required in manufactureand leaves the protection member unremoved, providing protection to thesemiconductor layer during a late step of mounting circuit componentsand even after the completion of the two-dimensional image detector.This provides substantially perpetual protection to the semiconductorlayer until the two-dimensional image detector is delivered as afinished product.

As a result, two-dimensional image detector having lasting highreliability can be manufactured with the active element array and thesemiconductor layer exhibiting a satisfactory level of performance.

Another method of manufacturing a two-dimensional image detector inaccordance with the present invention is a method of manufacturing atwo-dimensional image detector including:

a semiconductor layer for producing electric charges according toincident electromagnetic waves; and

a substrate having an active element array for reading out the electriccharges produced by the semiconductor layer,

the manufacturing method comprising the steps of:

(1) forming the active element array on the substrate;

(2) forming the semiconductor layer so as to cover the active elementarray;

(3) forming on the semiconductor layer a surface electrode layer throughwhich a bias voltage is applied to the semiconductor layer;

(4) forming a protection member on the substrate so as to cover thesemiconductor layer and the surface electrode layer; and

(5) dividing into smaller pieces the substrate on which the protectionmember is already formed.

According to the method, an active element array is formed on asubstrate, and topped sequentially by a semiconductor layer and asurface electrode layer. Then a protection member is formed on thesubstrate so as to cover the semiconductor layer and the surfaceelectrode layer. Thereafter, the substrate is divided with theprotection member being provided thereon.

Thus, a protection member is formed on the substrate to cover thesemiconductor layer and the surface electrode layer, and onlysubsequently the substrate is divided; therefore, glass particles andprocessing water produced or used during the division do not directlypollute the semiconductor layer and the surface electrode layer. Inother words, the protection member ensures that the semiconductor layerand the surface electrode layer are protected from pollution with glassparticles and processing water. Further, the active element array iscovered with a semiconductor layer protected by the protection member;therefore, the active element array per se is not polluted by glassparticles and processing water.

As a result, the active element array, the semiconductor layer, and thesurface electrode layer can be kept clean and free from scratches, andthe deterioration in performance of the active element array, thesemiconductor layer, and the surface electrode layer can be prevented.As a result, according co the method, highly reliable active matrixsubstrates are manufactured with the active element array operatingstably and the semiconductor layer and the surface electrode layerexhibiting a lasting satisfactory level of performance. So aretwo-dimensional image detectors in addition, the production yields ofthe active matrix substrates improve.

A two-dimensional image detector in accordance with the presentinvention includes:

a substrate;

an active element array provided on the substrate;

a semiconductor layer, provided on the active element array, forproducing electric charges according to incident electromagnetic wavesso that he electric charges are read out by the active element array;and

a protection member, provided on the substrate, for covering thesemiconductor layer.

According to the arrangement, a protection member is provided to coverthe semiconductor layer on the active element array; therefore,pollutants produced in the use of the two-dimensional image detector canbe prevented from directly contacting the active element array and thesemiconductor layer. Since the protection member is disposed on thesubstrate, a minimum area including the active element array and thesemiconductor layer can be protected. Therefore, when thetwo-dimensional image detector is disassembled thoroughly intocomponents for maintenance for example, the active element array and thesemiconductor layer are still protected from pollutants.

As a result, highly reliable two-dimensional image detectors can bemanufactured with the deterioration in performance of the active elementarray and the semiconductor layer being effectively prevented even afterthe manufacturing process.

Further, by providing the protection member so as to cover thesemiconductor layer, electric discharge can be prevented from happeningaround the semiconductor layer even when a high voltage is applied tothe semiconductor layer. This protects components from destruction dueto electric discharge, as well as prevents the aforementioned pollutionand deterioration in performance of the active matrix element and thesemiconductor layer. Furthermore, the protection member isolates thesemiconductor layer from ambient air, preventing dew drops fromdeveloping in, and thus degrading the properties of, the semiconductorlayer.

Another two-dimensional image detector in accordance with the presentinvention includes:

a substrate;

an active element array provided on the substrate;

a semiconductor layer, provided on the active element array, forproducing electric charges according to incident electromagnetic wavesso that the electric charges are read out by the active element array;

a surface electrode layer, provided on the semiconductor layer, forallowing a bias voltage to be applied to the semiconductor layer; and

a protection member, provided on the substrate, for covering thesemiconductor layer and the surface electrode layer.

According to the arrangement, a protection member is provided to coverthe semiconductor layer and the surface electrode layer on the activeelement array; therefore, pollutants produced in the use of thetwo-dimensional image detector can be prevented from directly contactingthe active element array, the semiconductor layer, and the surfaceelectrode layer.

Since the protection member is disposed on the substrate, a minimum areaincluding the active element array, the semiconductor layer, and thesurface electrode layer can be protected. Therefore, when thetwo-dimensional image detector is disassembled thoroughly intocomponents for maintenance for example, the active element array, thesemiconductor layer, and the surface electrode layer are still protectedfrom pollutants.

As a result, highly reliable two-dimensional image detectors can bemanufactured with the deterioration in performance of the active elementarray, the semiconductor layer, and the surface electrode layer beingeffectively prevented even after the manufacturing process.

Further, by providing the protection member so as to cover thesemiconductor layer and the surface electrode layer, electric dischargecan be prevented from happening around the semiconductor layer and thesurface electrode layer even when a high voltage is applied to thesemiconductor layer via the surface electrode layer. This protectscomponents from destruction due to electric discharge, as well asprevents the aforementioned pollution and deterioration in performanceof the active matrix element, the semiconductor layer, and the surfaceelectrode layer. Furthermore, the protection member isolates thesemiconductor layer and the surface electrode layer from ambient air,preventing dew crops from developing in, and thus degrading theproperties of, the semiconductor layer and the surface electrode layer.

For a fuller understanding of the nature and advantages of theinvention, reference should be made to the ensuing detailed descriptiontaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart showing manufacturing steps of a two-dimensionalimage detector of a first embodiment in accordance with the presentinvention.

FIG. 2(a) through FIG. 2(h) are cross-sectional views showing thetwo-dimensional image detector in those steps described in FIG. 1.

FIG. 3 is a perspective view schematically showing a basic structure ofthe two-dimensional image detector fabricated by those manufacturingsteps of the first embodiment in accordance with the present invention.

FIG. 4 is a cross-sectional view showing a pixel in the two-dimensionalimage detector shown in FIG. 3.

FIG. 5 is a plan view showing an overall arrangement of thetwo-dimensional image detector shown in FIG. 3.

FIG. 6 is a flow chart showing manufacturing steps of anothertwo-dimensional image detector of the first embodiment in accordancewith the present invention.

FIG. 7(a) through FIG. 7(i) are cross-sectional views showing thetwo-dimensional image detector in those steps described in FIG. 6.

FIG. 8 is a flow chart showing manufacturing steps of a two-dimensionalimage detector of a second embodiment in accordance with the presentinvention.

FIG. 9(a) through FIG. 9(g) are cross-sectional views showing thetwo-dimensional image detector in those steps described in 8.

FIG. 10(a) is a plan view showing a through hole provided in aprotection glass plate.

FIG. 10(b) is a plan view showing a notch provided to a protection glassplate.

FIG. 11 is a plan view showing a surface electrode pull-out holderprovided to a surface electrode layer.

FIG. 12 is a cross-sectional view schematically showing a structure ofan active matrix substrate (two-dimensional image detector) such thatthe protection glass plate includes a metal film.

FIG. 13 is a cross-sectional view showing a two-dimensional imagedetector fabricated by manufacturing steps modified based on thosemanufacturing steps described in FIG. 8.

FIG. 14 is a flow chart showing manufacturing steps in sequence, of atwo-dimensional image detector, which is a modified example of thesecond embodiment in accordance with the present invention.

FIG. 15(a) through FIG. 15(g) are cross-sectional views showing thetwo-dimensional image detector in those steps described in FIG. 14.

FIG. 16 is a cross-sectional view schematically showing a structure of atwo-dimensional image detector such that there is further provided asurface protection member so as to cover a surface protection film shownin FIG. 15(g).

FIG. 17 is a perspective view schematically showing a structure of aconventional two-dimensional image detector.

FIG. 18 is a cross-sectional view showing a structure of a pixel shownin FIG. 17.

DESCRIPTION OF THE EMBODIMENTS Embodiment 1

The following description will discuss an embodiment in accordance withthe present invention in reference to drawings.

First, referring to FIG. 3 through FIG. 5, a two-dimensional imagedetector fabricated by manufacturing steps of the present embodimentwill be explained.

FIG. 3 is a perspective view schematically showing a basic structure ofa two-dimensional image detector fabricated by manufacturing steps ofthe present embodiment. The two-dimensional image detector includes anactive matrix substrate 1, an X-ray conductive layer (semiconductorlayer, photoconductive film) 12, and a surface electrode layer (surfaceelectrode, upper electrode, electrode) 16.

The structure of the active matrix substrate 1 will be explained in thefollowing. The active matrix substrate 1 includes a glass substrate(substrate) 2, electrode wires (gate electrode line 4 a and dataelectrode line 4 b) 4 formed the class substrate 2, thin filmtransistors (hereinafter, will be referred to as TFTs) (active elements)6 acting as switching elements, electric charge storage capacitances 8,and pixel electrodes 10.

Each pixel 11 is chiefly constituted by a TFT 6, an electric chargestorage capacitance 8, and a pixel electrodes 10. The pixels 11 arearranged in a XY matrix (arranged in rows and columns). The TFT 6 isconnected at its gate and data electrodes 6 a and 6 b to the gate anddata electrode lines 4 a and 4 b respectively (see FIG. 4 detailedlater). The pixels 11, when arranged to form a XY matrix or otherregulated patterns, will be collectively referred to as a TFT array(active element array) 32. Sometimes, the area in which the TFT array 32is formed will be referred to as an active element formation area.

The gate electrode line 4 a extends along the rows of the active matrixsubstrate 1, being connected at its end to a driver LSI circuit (circuitcomponent) 22, whilst the data electrode line 4 b extends along thecolumns of the active matrix substrate 1, being connected at its end toan amplifier LSI circuit (circuit component) 20.

The surface electrode layer 16 is connected to a high voltage source 18so as to apply voltage to Cs electrodes 9 detailed later.

Now, referring to FIG. 4, the structure of the pixel 11 will beexplained in detail. FIG. 4 is a cross-sectional view showing a pixel 11in the two-dimensional image detector. The drain electrode 6 c of theTFT 6 is extended to form the pixel electrode 10. The pixel electrode 10is adapted so as to switch to the data electrode 6 b of the TFT 6 uponthe application of a signal to the gate electrode 6 a of the TFT 6through the gate electrode line 4 a (see FIG. 3), that is, to switchelectrical connection between the data electrode line 4 b (see FIG. 3)and the pixel electrode 10 (see FIG. 3).

Combined with the Cs electrode 9 across a gate insulation film 24, thepixel electrode 10 forms an electric charge storage capacitance 8. Theelectric charge storage capacitance 8 stores electrode charges from theX-ray conductive layer 12 as image information, when the high voltagesource 18 applies voltage across the Cs electrode 9 and the surfaceelectrode layer 16.

The TFT 6 has a structure made up of sequentially deposited thin film,including gate electrodes 6 a, a gate insulation film 24, and anamorphous silicon layer (a-Si layer, channel layer) 26. The TFT 6farther includes data electrodes 6 b and drain electrodes 6 c depositedon individual contact layers (a-Si (n⁻type) layers) 28 over the commonamorphous silicon layer 26.

An insulation protection film 30 is then formed to cover other partsthan those on the pixel electrode 10 of the pixel 11 and provideprotection to the TFT 6 and other members.

On the entirety of the active matrix substrate 1 except its periphery,there is provided an X-ray conductive layer 12 of, for example,amorphous selenium (hereinafter, will be referred to as a-Se). A surfaceelectrode layer 16 is further provided on the X-ray conductive layer 12.

The two-dimensional image detector was discussed in the foregoingdescription only in terms or ts basic structure, and in practice mayalso include other elements. For example, an electric charge preventionlayer or a dielectric layer (not shown) may be provided between theelectrodes and the X-ray conductive layer 12 to prevent current fromleaking through the pixel electrodes 10 and he surface electrode layer16

Now, the two-dimensional image detector will be discussed in terms orits operation principles in reference to FIGS. 3 and FIG. 4.

As X-rays enter he X-ray conductive layer 12, electric charges(electrons-holes) develop in the X-ray conductive layer 12. The X-rayconductive layer 12 here functions to convert the form of informationfrom electromagnetic wave to electric charges. The developing electronsand holes move toward the anode (toward the surface electrode layer 16in FIGS. 3 and 4) and the cathodes (toward the Cs electrodes 9 in FIGS.3 and 4) respectively due to the voltage applied by the high voltagesource 18 across the surface electrode layer 16 and the Cs electrodes 9,thereby building up electric charges in the electric charge storagecapacitances 8.

The electric charges thus accumulated in the electric charge storagecapacitance 8 are sent to the amplifier LSI circuit 20 through the dataelectrode line 4 b by changing the TFT 106 into an on-state by means ofan input signal from the driver LSI circuit 22 via the gate electrodelines 4 a. Since the electrode wires 4 (the gate electrode lines 4 a andthe data electrode lines 4 b) the TFTs 106, and the electric chargestorage capacitances 8 are arranged to form an XY matrix as explainedearlier, information on a two-dimensional radiation image is obtainableby sending an input signal sequentially to the gate electrode lines 4 a.

The overall arrangement of a two-dimensional image detector including abasic structure as discussed in the foregoing will be explained inreference to FIG. 5, which is a plan view showing the overallarrangement of a two-dimensional image detector fabricated by themanufacturing steps of the present embodiment.

As shown in FIG. 5, the active matrix substrate 1 includes pixels 11arranged to form an XY matrix except along the periphery of she activematrix substrate 1. The pixels 11 are covered by an X-ray conductivelayer 12 and a surface electrode layer 16. In FIG. 5, each smallestsquare surrounded by broken lines represents a pixel 11, and the pixels11 collectively form a TFT array 32. The area surrounded by the thicksolid lines indicates where the X-ray conductive layer 12 is provided.

Along the periphery of the active matrix substrate 1 there are providedamplifier LSI circuits 20 and driver LSI circuits 22. The amplifier LSIcircuits 20 and the driver LSI circuits 22 are connected to the dataelectrode lines 4 b and the gate electrode lines 4 a (see FIG. 3) by TAB(Tape Automated Bonding) or COG (Chip on Glass) technologies. Theconnection is not shown in FIG. 5. The driver LSI circuits 22 and theamplifier LSI circuits 20 are not fully shown; less than those actuallymounted are shown for illustrative purposes only.

Now, the two-dimensional image detector will be discussed in terms ofits manufacturing method in reference to drawings. FIG. 1 is a flowchart showing manufacturing steps for the two-dimensional image detectorof the present embodiment. FIG. 2(a) through FIG. 2(h) arecross-sectional views showing the two-dimensional image detector inthose steps described in FIG. 1.

As shown in FIG. 1, a manufacturing process for the two-dimensionalimage detector of the present embodiment includes a TFT arrayfabrication step (step P1), a surface protection layer formation step(step P2) a TFT array dividing step (step P3), an edge chamfering step(step P4), a surface protection layer removing step (step P5), an X-rayconductive layer formation step (step P6), a surface electrode layerformation step (step P7), and a mounting step (step P8). FIG. 2(a)through FIG. 2(h) shows cross-sections of the two-dimensional imagedetector in the respective steps. The following description will discussthe individual steps in reference to FIG. 2(a) through FIG. 2(h)

In the TFT array fabrication step (step 1), a TFT array 32 is fabricatedon a mother glass substrate (substrate) la similarly to a manufacturingstep for active matrix liquid crystal displays. Specifically, on themother glass substrate la there are provided electrode wires 4 (gateelectrode line 4 a data electrode line 4 b), TFTs 6 each for a pixel 11,electric charge storage capacitances 8, pixel electrodes 10, etc. (seeFIG. 3 or FIG. 4). FIG. 2(a) only shows the mother glass substrate 1 aand the pixel electrodes 10 for simple illustration (So do followingfigures)

Here, the mother glass substrate 1 a measures 550 mm ×650 mm×1.1 mm.Typically, the measurement of he mother glass substrate la depends onthe fabrication device for the TFT array 32, exclusively used forsubstrates of a particular size. An area of 430 mm×430 mm is reserved toaccommodate each TFT array 32, which is decided depending on the imagereadout area required for the two-dimensional image detector to bemanufactured.

The manufacturing method for the TFT array 32 is well known in the artof active matrix liquid crystal displays; specific, detailed descriptionis therefore omitted here.

In the following surface protection layer formation step (step P2), asurface protection layer (protection member) 34 is formed so as to coverthe area in which the TFT array 32 is formed on the mother glasssubstrate 1 a. Here, the surface protection layer 34 is made of aphotosensitive resin, or more specifically, for example, a photoresistused in photolithography in manufacture of liquid crystal displays andsemiconductor devices.

Photoresist is used in the following manner in manufacture of thesurface protection layer 34. Photoresist is deposited on the surface ofthe mother glass substrate 1 a with a thickness of about 2 μm by spincoating, and then exposed and developed similarly to ordinaryphotolithography process to pattern the photoresist.

Here, the pattern of the photoresist is such that there existsphotoresist where the TFT array 32 is formed and that there does notexist photoresist near dividing lines 1 b along which the mother glasssubstrate 1 a is divided into active matrix substrates 1 of a particularsize in the next step (step P3). The photoresist thus provided on themother glass substrate 1 a serves as a surface protection layer 34.

Alternatively to photoresist, the photosensitive resin may bephotosensitive acrylic and other resins of both negative and positivetypes. More specifically, photoresist OFPR (trademark) series areavailable from Tokyo Ohka Kogyo Co., Ltd and TFR (trademark) series areavailable from Teijin Ltd.

The foregoing description focused on the method of forming a surfaceprotection layer 34 from a photosensitive resin. Alternatively, thesurface protection layer 34 may be formed by other methods as follows.

A first example is printing, which would encompass screen, letterpress,intaglio, and other conventional printing. According to these printingmethods, non-photosensitive materials can be applied and patternedsimultaneously.

A further alternative is to use an aqueous resin (e.g., aqueous wax) toform a surface protection layer 34. A surface protection layer 34, whencomposed of an aqueous resin, can be removed in a later step of removingthe surface protection layer (step PS), using room-temperature or warmwater without special solvent. This alleviates negative effects ofsolvent of polluting the X-ray conductive layer 12 and the environment.

Aqueous resins may be applied by spin coating similarly to theforegoing. Additionally, if the aqueous resin has thermal plasticity, aconventionally known method may be used whereby the resin is appliedwhile being heated. In any event, if the aqueous resin is notphotosensitive, it should be either applied with a tool or the likeproviding protection to the vicinity of the dividing lines 1 b orapplied on the entirety of the mother glass substrate 1 a andsubsequently partly removed near the dividing lines 1 b.

In the TFT array dividing step (step P3), the mother glass substrate 1 ais divided into active matrix substrates 1 of a predetermined size. Theactive matrix substrate 1 needs to be large enough to allow theformation of the TFT array 32 (here, 430 mm×430 mm), plus a surroundingarea in which drive circuits (amplifier LSI circuits 20, driver LSIcircuits 22 as shown in FIG. 5) are mounted here, the active matrixsubstrate 1 measures 480 mm×480 mm.

The mother glass substrate 1 a is cut by a diamond scribe technology.According to a diamond scribe technology, glass or a like material isdivided into pieces by applying force to micro cracks that are formed bydrawing scribe lines on the surface of the glass, etc. with a diamondblade. Diamond scribe technologies need only inexpensive devices andboast excellent throughput (performance). On the other hand, theirdrawbacks include likely scattering of broken, small pieces of glass(cullets) when drawing scribe lines.

However, in the present embodiment, the surface protection layer. 34 isprovided in the surface protection layer formation step (step P2) so asto cover the area in which the TFT array 32 is formed, effectivelypreventing small pieces of glass from sticking directly to the surfaceof the TFT array 32. Hence, the TFT array 32 is protected from pollutionand scratches.

Further, in the present embodiment the surface protection layer 34 isdeposited and patterned in the surface protection layer formation step(step P2) so that there exists no surface protection layer 34 near thedividing lines 1 b. This facilitates drawing scribe lines.

Alternatively to the diamond scribe technology, the mother glasssubstrate 1 a may be divided by dicing using, for example, a diamondblade. According to the method, the cutting process is performed whilepouring processing water over portions to be cut. The process thereforeentails production of pollutants such as processing water, glassparticles due to abrasion, particles due to wearing of the blade. Inthis method, similarly to the foregoing case, the surface protectionlayer 34 provides protection to the TFT array 32 from these pollutants.

The edges of the sides of the active matrix substrate 1, along which thesubstrate 1 was cut off by a diamond scribe or dicing technology, isfragile and easy to break. Preferably, the edges are subjected tochamfering in the next edge chamfering step (step P4).

In the edge chamfering step (step P4), the edges are chamfered.Typically, in a chamfering process, the chamfered portions (edges) arepolished using grind stone while pouring processing water to thoseportions. The present embodiment adopts this method. This process alsoentails production of pollutants such as processing water, glassparticles due to abrasion, particles due to wearing of the blade. Inthis method also, similarly to the TFT array dividing step (step P3),the surface protection layer 34 provides protection to the TAT array 32from these pollutants.

Next, in the surface protection layer removing step (step P5), thesurface protection layer 34 is removed from the active matrix substrate1. If the surface protection layer 34 is composed of photoresist, it ispreferable to remove the surface protection layer 34 using a dedicatedresist removing liquid. Other kinds of organic solvents are alsoavailable. If the surface protection layer 34 is composed of aqueousresin, it is removable using room-temperature or warm water; supersonicwashing or the use of a jacuzzi would enhance the results.

Next, in the X-ray conductive layer formation step (step P6), an X-rayconductive layer 12 is formed on the active matrix substrate 1. Here,the X-ray conductive layer 12 is formed by depositing an a-Se film byvacuum vapor deposition. The a-Se film is deposited with a thickness ofabout 500 μm to 1500 μm, so as to cover almost the entirety of the areain which the TFT array 32 is formed.

Here, the surface of the active matrix substrate 1, serving as a bed onwhich the X-ray conductive layer 12 will be formed, is protected frompollutants, and thus kept clean, by the surface protection layer 34.Therefore, the a-Se film formed thereon has very stable properties.

Next, in the surface electrode layer formation step (step P7), a surfaceelectrode layer 16 is formed on she X-ray conductive layer 12. Here, Au(gold) is deposited with a thickness of about 0.5 μm as the surfaceelectrode layer 16 by vacuum vapor deposition.

Next, in the mounting step (step P8), driver LSI circuits 22 andamplifier LSI circuits 20 are mounted to the periphery of the activematrix substrate 1 by the aforementioned TAB or COG technology. Itshould be noted that the mounting is performed with the temperature ofthe active matrix substrate 1 under control so that the heat generatedby the process does not increase the temperature so much as to cause thea-Se film, serving as the X-ray conductive layer 12, to crystalize. Inthe present embodiment, TAB technology is used in the mounting processas an example.

Also, a sensor bias lead 16 a for connecting the surface electrode layer16 to the high voltage source 18 (see FIG. 3) is attached to the surfaceelectrode layer 16.

The two-dimensional image detector thus fabricated subsequentlyundergoes assembly steps in which the high voltage source 18 (see FIG.3) and other components will be attached to complete the entiremanufacturing process. Description of those subsequent steps is omitted.

Step P6 to step P8 may be executed in a different order from that shownin FIG. 1; namely, in the order of the mounting step (step P8), theX-ray conductive layer formation step (step P6), and the surfaceelectrode layer formation step (step P7).

If the three steps are arranged in the above order, the TFT array 32 isprotected by the surface protection layer 34 in the TFT array dividingstep (step P3) and the edge chamfering step (step P4); therefore, theTFT array 32 does not get in direct contact with pollutants produced inthe steps. This maintains the performance or the TFT array 32 at asatisfactory level and improves the qualities of the X-ray conductivelayer 12. As a result, the production yields and reliability oftwo-dimensional image detectors improve in the manufacturing process orthe present embodiment.

In the foregoing description about the present embodiment,two-dimensional image detectors for detecting X-ray images werediscussed, and a reference was made to the X-ray conductive layer 12serving as a photoconductive film. However, the present invention is notlimited to this: electromagnetic waves in various wavelength rangesincluding visible, infrared, and ultraviolet light, as well as X-rays,can be used. To handle electromagnetic waves other than X-rays, theX-ray conductive layer 12 should be adjusted so as to properly handlethe target electromagnetic waves.

The a-Se film used above as the X-ray conductive layer 12 exhibits asatisfactory level of photoconductivity to visible light. To takeadvantage of this characteristic, studies are under way to developsupersensitive image sensors by means of the avalanche effect under highvoltage application. The present invention is also effective if used inthe manufacture of the supersensitive image sensors.

The aforementioned phenomenon of crystallization (deterioration) of thea-Se film due to pollution or heat is commonly observed among amorphousmaterials, although crystallization temperature may differ from materialto material. Therefore, the present invention is effective with aphotoconductive film made of amorphous Si, amorphous SiC, amorhous SiGeto name a few.

Further, in the foregoing description, manufacture of two-dimensionalimage detectors including an X-ray conductive layer 12 was discussed;however, the steps preceding the formation of the X-ray conductive layer12 are identical to the steps of manufacturing the active matrixsubstrate 1. Therefore, besides two-dimensional image detectors, thepresent invention is further applicable to manufacturing steps fordevices incorporating an active matrix substrate 1, for example, liquidcrystal displays.

Modification Example

Now, referring to drawings, the following description will discuss amodification example of the present embodiment. FIG. 6 is a flow chartshowing the manufacturing steps in sequence for a two-dimensional imagedetector of the present modification example. FIG. 7(a) through FIG.7(i) are cross-sectional views showing the two-dimensional imagedetector in those steps described in FIG. 6.

As shown in FIG. 6, in accordance with the present modification example,the manufacturing stews or a two-dimensional image detector include aTFT array fabrication step (step P1), a surface protection layerformation step (step P2), a TFT array dividing step (step P3), an edgechamfering step (step P4), a driver and amplifier mounting step (step P8a), a surface protection layer removing step (step P5), an X-rayconductive layer formation step (step P6), a surface electrode layerformation step (step P7), and a bias lead mounting step (step P8 b).

FIG. 7(a) through FIG. 7(i) show cross sections of the two-dimensionalimage detector in the respective steps. The following description willdiscuss the individual steps in reference to corresponding FIG. 7(a)through FIG. 7(i). Here, for convenience, the steps that are essentiallyidentical to the steps discussed above are indicated by the samereference numerals and description thereof is omitted.

In the present modification example, the mounting step (step P8)discussed above will be divided into two steps, that is, a driver andamplifier mounting step (step P8 a) and a bias lead mounting step (stepP8 b). The driver and amplifier mounting step (step P8 a) is executedbetween the edge chamfering step (step P4) and the surface protectionlayer removing step (step P5).

Specifically, the driver LSI circuits 22 and the amplifier LSI circuits20 are mounted (driver and amplifier mounting step (step P8 a))immediately after completing the edge chamfering step (step P4), beforeremoving the surface protection layer 34 covering the TFT array 32. Thecircuits are mounted in the same manner as in the foregoing case.

Here, mounting the driver LSI circuits 22 and the amplifier LSI circuits20 entails attachment by means of heat, for example, anisotropicconductive connection using an AC (anisotropic conductive film) or wirebonding connection using solder. Pollutant gases and dust may beproduced in the processes and pollute the TFT array 32 and the X-rayconductive layer 12. However, in the present modification example, whendriver LSI circuits 22 and the amplifier LSI circuits 20 are mounted,the TFT array 32 is protected by the surface protection layer 34, andthe X-ray conductive layer 12 is yet to be formed. Therefore the TFTarray 32 and the X-ray conductive layer 12 are not polluted.

After mounting the driver LSI circuits 22 and the amplifier LSI circuit20, the surface protection layer 34 is removed in the surface protectionlayer removing seep (step P5). The process then proceeds to the X-rayconductive layer formation step (step P6) and the surface electrodelayer formation step (step P7).

The surface electrode layer 16 is formed in the surface electrode layerformation step (step P7), and thereafter a sensor bias lead 16 a isattached to the surface electrode layer 16 in the bias lead mountingstep (step P8 b).

In the foregoing process, the TFT array 32 is protected by the surfaceprotection layer 34 in the driver and amplifier mounting step (step P8a), as wells as in the TFT array dividing step (step P3) and in the edgechamfering step (step P4). The X-ray conductive layer 12 is formed aftercompleting these steps. Hence, the TFT array 32 and the X-ray conductivelayer 12 do not get in direct contact with the pollutants produced inthese steps.

This better maintains the performance of the TFT array 32 at asatisfactory level, and further improves the qualities of the X-rayconductive layer 12. As a result, the production yields and reliabilityof two-dimensional image detectors improve in the manufacturing processof the modification example.

In the foregoing process, the driver and amplifier mounting step (stepP8 a) is executed before the X-ray conductive layer formation step (stepP6); there ore, heat treatment during mounting the drivers andamplifiers would not negatively affect the X-ray conductive latter 12.

Embodiment 2

Referring to drawings, the following description will discuss anotherembodiment in accordance with the present invention. Here, forconvenience, members of the present embodiment that have the samearrangement and function as members of embodiment 1 are indicated by thesame reference numerals and description thereof is omitted.

FIG. 8 is a flow chart showing the manufacturing steps in sequence for atwo-dimensional image detector of the present embodiment. FIG. 9(a)through FIG. 9(g) are cross-sectional views showing the two-dimensionalimage detector in those steps described in FIG. 3.

As shown in FIG. 8, in accordance with the present embodiment, themanufacturing steps for the two-dimensional image detector include a TFTarray fabrication step (step P1), an X-ray conductive layer formationstep (step P6), a surface electrode layer formation step (step P7), asurface protection member formation step (step P2 a), a TFT arraydividing step (step P3), an edge chamfering seep (step P4), and amounting step (step P8 c).

FIG. 9(a) through FIG. 9(g) show cross sections of the two-dimensionalimage detector in the respective steps. The following description willdiscuss the individual steps in reference to corresponding FIG. 9(a)through FIG. 9(g). Here, for convenience, the steps identical to thesteps discussed in embodiment 1 are indicated by the same referencenumerals and description thereof is partly omitted.

First, a TFT array 32 is formed on the mother glass substrate 1 a in theTFT array fabrication step (step P1).

Next, an a-Se film is formed as an X-ray conductive layer 12 in theX-ray conductive layer formation step (step P6), Here, since the X-rayconductive layer 12 is formed immediately after the formation of the TFTarray 32 on the mother glass substrate 1 a, there is little likelihoodfor the surface of the TFT array 32 serving as a bed on which the X-rayconductive layer 12 is formed to be polluted. Therefore, the TFT array32 is not polluted, and the X-ray conductive layer 12 manufactured has asatisfactory level of quality, enabling the TFT array 32 and the X-rayconductive layer 12 fabricated to show very stable performance.

Next, in the surface electrode layer formation step (step P7), a surfaceelectrode layer 16 is formed on the X-ray conductive layer 12.

Next, in the surface protection member formation step (step P2 a), asurface protection member (protection member) 35 is provided in place ofsurface protection layer 34 (see FIG. 2(b) through FIG. 2(d)) ofembodiment 1. The surface protection member 35 is constituted by aprotection glass plate 35 a, a sealant (connecting member) 35 b, and asealing tape 3 c.

The surface protection member 35 proves protection to the X-rayconductive layer 12 and the surface electrode layer 16 in the followingmanner.

First, a sealant 35 b is provided surrounding the X-ray conductive layer12 along the circumference of an area in which the X-ray conductivelayer 12 is provided on the mother glass substrate 1 a. The sealant 35 bsuitably establishes satisfactory adhesion between the mother glasssubstrate 1 a and the protection glass plate 35 a and cures withoutthermally affecting the a-Se film. Preferred examples of such a sealant35 b include light-curing glues and silicon sealants.

A protection glass plate 35 a, cleaned beforehand, is disposed oppositeto the mother glass substrate 1 a, sandwiching the sealant 35 b so as tocover the X-ray conductive layer 12 and the surface electrode layer 16.The protection glass plate 35 a here is 0.7 mm thick.

If the protection glass plate 35 and the mother glass substrate 1 a aremade of the same material as in the foregoing and thus share an equalcoefficient of thermal expansion, even when they are secured, thesubstrate does not warp due to difference in thermal expansion. Theprotection glass plate 35 a may be replaced by a sheet of PET(polyethylene terepht-halate) or another similar resin.

The protection glass plate 35 a is provided with a through hole 35 dthrough which a sensor bias lead 16 a is mounted later. The through hole35 d is sealed in advance with a sealing tape 35 c. Alternatively, thethrough hole 35 d may be formed on the mother glass substrate 1 a afterthe provision of the sealant 35 b on the protection glass plate 35 a.

Here, the gaps between the sealant 35 b and the mother glass substrate 1a, between the sealant 33 b and the protection glass plate 35 a, andbetween the sealing tape 35 c and the protection glass plate 35 a arehermetically sealed. The sealing prevents processing water and glassparticles used or produced in a later step from sneaking into thesurface protection member 35, and provides protection to the X-rayconductive layer 12 and the surface electrode layer 16 from pollutants.

Next, in the TFT array dividing step (step P3), the mother glasssubstrate 1 a is divided into active matrix substrates 1 of apredetermined size. Then, in the edge chamfering step (step P4), thesides of the active matrix substrate 1, along which the substrate 1 wascut off, are chamfered.

Here, as detailed in embodiment 1, either diamond scribe or dicing usinga diamond blade is carried out, following by polishing using a grindstone. The active matrix substrate 1 directly contacts pollutants, suchas glass particles and processing water produced or used in the process,as discussed in the foregoing; however, in the present embodiment, thesurface protection member 35 protects the X-ray conductive layer 12 andthe surface electrode layer 16 from pollution or scratches similarly toembodiment 1.

Next, in the mounting step (step P8 c), the driver LSI circuits 22, theamplifier LSI circuits 20, and the sensor bias lead 16 a are mounted.The driver LSI circuits 22 and amplifier LSI circuits 20 are mounted inthe same manner as in the mounting step (step P8) in embodiment 1,whilst the sensor bias lead 16 a is connected to the surface electrodelayer 16 at one end through a through hole 35 d opened by peeling thesealing tape 35 c off the protection glass plate 35 a, and extendsexternally at the other end.

The driver LSI circuits 22 and amplifier LSI circuits 20 are preferablymounted while the through hole 35 d is sealed by the sealing tape 35 c.This prevents, similarly to the modified example of embodiment 1,pollution of the X-ray conductive layer 12 and the surface electrodelayer 16 during mounting the driver LSI circuits 22 and the amplifierLSI circuits 20.

FIG. 10(a) is a top view, as seen oppositely from the mother glasssubstrate 1 a across the protection glass plate 35 a in FIG. 9(d),showing the through hole 35 d provided in the protection glass plate 35a through which the sensor bias lead 15 a extends externally.Alternatively, for example, as shown in the plan view constituting FIG.10(b), a notch 35 e may be provided in a corner or along a periphery ofthe protection glass plate 35 a in advance, to expose a part of thesurface electrode layer 16, where the sensor bias lead 16 a is mounted.

A further alternative is shown in FIG. 11, in which neither a throughhole 35 d nor a notch 35 e is provided in the protection glass plate 35a. Instead, a surface electrode pull-out holder 16 b may be formed bypartly extending the surface electrode layer 16 to provide externalaccess to the protection glass plate 35 a.

The through hole 35 d, notch 35 e, or surface electrode pull-out holder16 b, since required to be located outside areas where the driver LSIcircuits 22 and the amplifier LSI circuits 20 for the active matrixsubstrate 1 are disposed, is preferably disposed in a corner of theprotection glass place 35 a or its corresponding part of the surfaceelectrode layer 16. Through holes 35 d or notches 35 e may be providedin plurality, for example, in all the four corners or two diagonallyopposing corners of the protection glass plate 35 a. Similarly, surfaceelectrode pull-out holders 16 b may be provided in plurality extendingfrom the surface electrode layer 16.

The provision of the through hole 35 d or notch 35 e in the protectionglass plate 35 a or the surface electrode pull-out holder 16 b extendingfrom the surface electrode layer 16 facilitates the mounting of thesensor bias lead 16 a. The provision further facilitates the applicationof a bias voltage to the surface electrode layer 16 via the through hole35 d, notch 35 e, or surface electrode pull-out holder 16 b, even withthe protection glass plate 35 a being provided above the mother glasssubstrate 1 a.

Preferably, the inside of the surface protection member 35 (the spacedefined by the surface protection member 35 and the active matrixsubstrate 1) is filled with an electrically insulating material by usingthe sealant 35 b again after the mounting step (step P8 c).

Preferred examples of electrically insulating materials includeinsulating gases, such as N₂; and electrically insulating materials,such as silicon oil KF96 manufactured by Shin-Etsu Chemical Co., Ltd andinactive liquid Florinate FC-40 manufactured by Sumitomo 3M Ltd.

The arrangement can prevent a high voltage across the surface electrodelayer 16 and the Cs electrodes 9 (see FIG. 4) from causing electricdischarge. The arrangement can also prevent ambient moisture fromforming dew drops and polluting the X-ray conductive layer 12 and theTFT array 32, and improve insusceptibility of the two-dimensional imagedetector to environment conditions.

An Al, Ni, or another metal film 45 may be provided, as shown in FIG.12, on the substantial entirety of the external surface of theprotection glass plate 35 a (opposite the surface of the protectionglass plate 35 a facing the X-ray conductive layer 12). The metal film45 thus provided improves on electric shield and light shelter of thetwo-dimensional image detector, and prevents a high voltage applicationfrom causing a build-up of static electricity.

In the TFT array dividing step (step P3), the edge chamfering step (stepP4), and the mounting step (step P8 c) among the above steps, the TFTarray 32 and the X-ray conductive layer 12 are protected by the surfaceprotection member 35. Therefore, in these steps, pollutants produced canbe prevented from directly contacting the TFT array 32 and the X-rayconductive layer 12, which maintains the performance of the TFT array 32at a satisfactory level and improves the qualities of the X-rayconductive layer 12. As a result, the production yields and reliabilityof two-dimensional image detectors improve.

The surface protection member 35 may be formed after the two-dimensionalimage detector is completely fabricated, to provide substantiallyperpetual protection to the area where the X-ray conductive layer 12 isformed and to preventing to some degree electric discharge and dew dropsfrom developing inside the surface protection member 35. This furtherimproves the reliability and insusceptibility of the two-dimensionalimage detector to environmental conditions.

In addition, the surface protection member 35 is disposed on the activematrix substrate 1; therefore, the surface protection member 35 providesprotection to a minimum area including the TFT array 32 and the X-rayconductive layer 12. Therefore, when the two-dimensional image detectoris disassembled thoroughly into components for maintenance for example,the TFT array 32 and the X-ray conductive layer 12 are still protectedfrom pollutants.

In the description so far, the surface protection member 35 wasconstituted by a protection glass plate 35 a by way of example; however,a ceramic substrate or a resin sheet (plate) may be used in place of theprotection glass plate 35 a. The use of a solid substrate composed of aceramic substrate (including glass substrate) is advantageous in thatthe substrate in which the active element array is provided isreinforced. Meanwhile, the use of a solid substrate composed of a resinsheet (plate) is advantageous in that the substrate becomes easy tofabricate, which facilitates the formation of the through hole andnotch, and also in that the smaller weight of the substrate than aceramic substrate allows a reduction in the weight of thetwo-dimensional image detector.

The alternative member to the protection glass plate 35 a is preferablycomposed of material that does not interfere with incident X-rays intothe X-ray conductive layer 12. A preferred example of such a ceramicsubstrate is composed of one of the ceramic materials consisting ofaluminum oxide, aluminum nitride, boron nitride, silicon oxide, siliconnitride, and silicon carbide. The ceramic substrates absorb only limitedamounts of X-rays; therefore the use of the ceramic substrates does notcause a significant drop in the sensitivity of the two-dimensional imagedetector. By contrast, a ceramic substrate containing a relatively largeproportion of an element of a large atomic number, such as Ba, Pb, orSn, absorbs large portions cf X-rays and likely to degrades thesensitivity of the two-dimensional image detector.

If two or more of the foregoing ceramic materials are used in mixture,the coefficient of thermal expansion of the ceramic substrate can bearbitrarily adjusted by changing the ratio of the mixture. Accordingly,a ceramic substrate can be fabricated with a coefficient of thermalexpansion substantially equal to that of the substrate on which theactive element array is formed. The ceramic substrate does not warp dueto a difference in coefficients of thermal expansion even when both thesubstrates (the ceramic substrate and the substrate on which the activeelement array is formed) are secured.

A resin sheet (plate) will absorb only limited amounts of X-rays andhardly degrade the sensitivity of the two-dimensional image detector.Especially, if the sheet (plate) is made of a resin material containingno Si, these advantages are enhanced. Such resin materials containing noSi include acrylic resins, polycarbonate (PC), polyethyleneterephthalate (PET), polystyrene, polyimide, polyvinyl chloride resin,nylon, BS resins, polyethylene, polypropylene. For example, to comparethe ceramic substrate with the resin sheet in terms or absorption ofX-rays, if both the substrates are 1 mm thick, the ceramic substrateabsorbs an average of about 10% of X-rays, while the resin sheet (plate)absorbs an much lower average of about 3%. Further, the resin sheet canbe fabricated with such a small thickness that the sheet becomesflexible, which is useful in allowing a further reduction in theabsorption of X-rays.

For the reasons laid out above, the surface protection member 35 iscomposed of a material that does not interfere with incident X-rays intothe X-ray conductive layer 12. In the description that follows, the samemember(s) as in the description above is(are) provided on the X-rayconductive layer 12 after the completion of the two-dimensional imagedetector.

If there is a surface protection member 35 provided in a two-dimensionalimage detector in the foregoing manner, electricity may be supplied tothe surface electrode layer 16 in a different manner as shown in FIG.13. FIG. 13 is a cross-sectional view showing a two-dimensional imagedetector, which is an application of the manufacturing steps fortwo-dimensional image detectors of the present embodiment.

The two-dimensional image detector includes a conductive layer 40provided on a surface of the protection glass plate 35 a facing thesurface electrode layer 16, and a conductive material (conductivemember) 42 is filling the space between the protection glass plate 35 aand the surface electrode layer 16. A sensor bias lead 16 a is connectedto the conductive layer 40 where there are no X-rays entering the X-rayconductive layer 12 (for example, as shown in FIG. 13, parts of theprotection glass plate 35 a not facing the X-ray conductive layer 121.

The structure provides alternative mounting positions for the sensorbias lead 15 a through which electricity is fed to the surface electrodelayer 16 which in turn applies an electric field across the X-rayconductive layer 12. Thus, the sensor bias lead 16 a does not exist inthe paths of incoming X-rays, does not cast a shadow in the producedX-ray image, effectively improving the image quality.

The existence of the conductive material 42 causes the vicinity of theX-ray conductive layer 12 to have an identical potential, and thus canprevent electric charge from occurring around the X-ray conductive layer12, similarly to the case where a electrical insulating material isfilling the gap between the protection glass plate 35 a and the surfaceelectrode layer 16.

To fabricate such a two-dimensional image detector, a protection glassplate 35 a including a prefabricated conductive layer 40 on one of itssurfaces should be used in the aforementioned step, and the conductivematerial 42 should be positioned in the gap between the surfaceelectrode layer 16 and the conductive layer 40 in the surface protectionmember formation step (step P2 a) followed by establishing connection ofthe sensor bias lead 16 a at the aforementioned position in the mountingstep (step P8 c). The conductive material 42 is preferably a conductiverubber sheet, a conductive adhesive sheet, a conductive paste, aconductive glue, and the like. Especially preferred among these arematerials containing carbon as a conductive pigment, because carbonabsorbs relatively small amounts of X-rays. Note that in such an eventno through hole 35 d is required.

Alternatively, the surface protection member formation step (step P2 a)is carried out by the use of a protection glass plate 35 a including aprefabricated conductive layer 40 on one of its surface in theaforementioned step, and the sensor bias lead 16 a is connected at theaforementioned position, and a conductive material 42 is injectedthrough the through hole 35 d in the mounting step (step P8 c). In suchan event, preferable examples of the conductive material 42 include aconductive liquid crystal, a conductive resin, and a liquid metal.

Now, characteristics, functions, and advantages of the two-dimensionalimage detector fabricated by the aforementioned steps will be summarizedas follows.

A two-dimensional image detector fabricated in accordance with thepresent embodiment is characterized in that it includes:

a substrate (glass substrate 2);

an active element array (TFT array 32) disposed on the substrate;

a semiconductor layer, provided on the active element array, forproducing electric charges according to incident electromagnetic waves,so that the active element array can read out the produced electriccharges; and

a protection member (surface protection member 35) provided on thesubstrate to cover the semiconductor layer (X-ray conductive layer 12).

The arrangement prevents those pollutants produced during the use of thetwo-dimensional image detector from directly contacting the activeelement array, the semiconductor layer, etc., effectively preventingquality deterioration of the active element array and the semiconductorlayer and offering highly reliable two-dimensional image detectors.

In the arrangement, a portion of the protection member oppositely facingthe semiconductor layer is preferably constituted by a solid substrate(protection glass plate 35 a).

According to the arrangement, the solid substrate may be composed of,for example, a glass substrate, a resin sheet, or other solid materialscontaining no solvents and the like that act as pollutants to thesemiconductor layer. Therefore, even if the protection member contactsthe semiconductor layer, the semiconductor layer is not polluted.

Furthermore, the two-dimensional image detector is preferably such thatthe protection member is hermetic.

According to the arrangement, the protection member seals out thesemiconductor layer from ambient air. Therefore, dew drops and otherphenomena can be prevented from developing due to the environment inwhich the two-dimensional image detector is used, more effectivelypreventing deterioration in performance of the active element array andthe semiconductor layer. Thus, the two-dimensional image detectorbecomes more reliable.

Furthermore, the two-dimensional image detector may be such that thereexists an insulating member filling a gap between the semiconductorlayer and the protection member.

According to the arrangement, there exists an insulating member fillinga gap between the semiconductor layer and the protection member;therefore, electric discharge does not happen around the semiconductorlayer even when a high voltage is applied across the semiconductor layerduring the use of the two-dimensional image detector, preventingdeterioration in performance of the semiconductor layer due to electricdischarge, as well as the aforementioned pollution of the active matrixelement and the semiconductor layer. Thus, Thus, the two-dimensionalimage detector becomes more reliable.

Furthermore, the two-dimensional image detector is preferably such thatthe insulating member is an insulating gas.

The insulating member, which is a gas, can better fill the gap betweenthe semiconductor layer and the protection member.

Furthermore, the two-dimensional image detector preferably includes:

electrodes (surface electrode layer 16) provided on the semiconductorlayer;

a conductive layer 40 provided on a surface of the protection memberoppositely facing the electrodes; and

a conductive material 42 filling a gap between the electrodes and theconductive layer.

According to the arrangement, the sensor bias lead 16 a does not existin the paths of incoming X-rays, does not cast a shadow in the producedX-ray image, effectively preventing the image quality deterioration.

Especially these advantages are ensured by, as shown in FIG. 13,providing the conductive layer 40 on the protection glass plate(protection member, attached substrate) 35 a above, and beyond theborders of, the surface electrode layer 16, and connecting the sensorbias lead 16 a to a part of the conductive layer 40 extending beyond theborders of the surface electrode layer 16.

Modification Example

Now, referring to drawings, the following description will discuss amodification example of the present embodiment. FIG. 14 is a flow chartshowing manufacturing steps in sequence for a two-dimensional imagedetector of the present modification example. FIG. 15(a) through FIG.15(g) are cross-sectional views showing the two-dimensional imagedetector in those steps described in FIG. 14.

As shown in FIG. 14, in accordance with the present modificationexample, the manufacturing steps for a two-dimensional image detectorinclude a TFT array fabrication step (step P1), an X-ray conductivelayer formation step (step P6), a surface electrode layer formation step(step P7), a surface protection film formation step (step P2 b), a TFTarray dividing step (step P3), an edge chamfering step (step P4), and amounting step (step P8 d).

FIG. 15(a) through FIG. 15(g) are cross-sectional views showing thetwo-dimensional image detector in the respective steps. Now, the stepswill be discussed in reference to corresponding FIG. 15(a) through FIG.15(g). Here, for convenience, the steps that are essentially identicalto the steps discussed above are indicated by the same referencenumerals and description thereof is partly omitted.

In the foregoing discussion, the surface protection member 35 providedincluded a protection glass plate 35 a and a resin sheet. In the presentmodification example, a surface protection film (protection member) 36is formed in place of the surface protection member 35, by the use of aresin that can be molded at room temperature.

First, the TFT array fabrication step (step P1), the X-ray conductivelayer formation step (step P6), and the surface electrode layerformation step (step P7) are executed in the same manner as in theforegoing.

Next, in the surface protection film formation step (step P2 b), asurface protection film 36 is formed in place of the surface protectionmember 35 (see FIG. 9(d) through FIG. 9(g)).

Here, if the surface protection film 36 needs to be heated during itsfabrication, the a-Se film serving as an X-ray conductive layer 12 islikely to crystallize. The crystallization of the a-Se film is promptedat relatively low temperatures of 60° C. to 80° C. (heat resistanttemperature). The a-Se film deteriorates in terms of photoelectricconversion characteristics when heated above the heat resistanttemperature.

For these reasons, the surface protection film 36 is suitably composedof a material that can be molded below the heat resistant temperature ofthe X-ray conductive layer 12, for example, a light-curing material orroom-temperature curing resin. Specifically, the material for thesurface protection film 36 may be selected from a wide range ofmaterials including light-curing acrylic resins, two-part-curing epoxyresins, one-part-curing and two-part-curing silicone resins,two-part-curing polyurethane resins, two-part-curing polyester resins.Alternatively, we can say that light-curing resins and silicon sealantsthat can cure at room temperature can be used to form the surfaceprotection film 36.

Composed of one of these materials, a resin layer is formed as thesurface protection film 36 so as to cover the X-ray conductive layer 12.The surface protection film 36 can be fabricated by printing or spraycoating using a mask, so as to cover only the X-ray conductive layer 12and its immediate vicinity. Here, printing includes screen, letterpress,intaglio, and other conventional printing. With spray coating, vaporresin, which will constitute the surface protection film 36, is sprayedonto a mother glass substrate 1 a partly masked where no surfaceprotection film 36 is to be formed.

Alternatively, a flexible sheet composed of an acrylic resin, an epoxyresin, a silicone resin, a urethane resin, or a polyimide resin may bepasted (or transferred) where there exist the X-ray conductive layer 12or the surface electrode layer 16, using a adhesive agent (or a glue),to form a surface protection film 36. In such a case, since a resinmaterial that is already in a solid state when provided to the motherglass substrate 1 a is used as the solid substrate, it becomes possibleto use a resin (e.g., polyimide resin) that cures at room temperature asthe surface protection film 36.

In other words, adhesive sheet (adhesive tape) composed of a polyimideor similar insulating flexible sheet may be paster where the X-rayconductive layer 12 is provided on the mother glass substrate 1 a, so asto form a surface protection film 36. This method is simple andconvenient, and can facilitate the fabrication of the surface protectionfilm 36.

As explained in the foregoing, the single surface protection film 36thus formed on the mother glass substrate 1 a so as to cover and contactthe X-ray conductive layer 12 can prevent electric discharge and dewdrops from occurring or developing in the X-ray conductive layer 12.

Next, following the same procedures as those explained in the foregoing,the TFT array dividing step (step P3) and the edge chamfering step (stepP4) are executed in sequence.

These two steps are followed by the mounting step (step P8 d). In thisstep, the driver LSI circuit 22, the amplifier LSI circuit 20, etc. aremounted in the same manner as in the mounting step (step P8 c). Thesensor bias lead 16 a is mounted by providing a hole in a part of thesurface protection film 36 to give access to the surface electrode layer16 and connecting the sensor bias lead 16 a to the surface electrodelayer 16 through the hole.

In the step above, as in the foregoing, pollutants are prevented fromdirectly contacting the TFT array 32, the X-ray conductive layer 12,etc, which maintains the performance of the TFT array 32 at asatisfactory level and improves the qualities of the X-ray conductivelayer 12. As a result, the production yields and reliability oftwo-dimensional image detectors improve.

The surface protection film 36 may be left unremoved after thecompletion of the two-dimensional image detector, giving substantiallyperpetual protection to the area where the X-ray conductive layer 12 isformed. The surface protection film 36 thus can maintain a state inwhich electric discharge or dew drops are unlikely to occur in the X-rayconductive layer 12. This further improves the reliability andinsusceptibility of the two-dimensional image detector to environmentalconditions.

After completely forming the surface protection film 36 in the presentmodification example, as shown in FIG. 16, a surface protection member35 may be further provided as in FIG. 9(d). The provision enhances theprotection of the X-ray conductive layer 12.

Now, characteristics, functions, and advantages of the two-dimensionalimage detector fabricated by the aforementioned steps will be summarizedas follows.

A two-dimensional image detector fabricated in accordance with thepresent embodiment is characterized in that it includes:

a substrate (glass substrate 2);

an active element array (TFT array 32) disposed on the substrate;

a semiconductor layer, provided on the active element array, forproducing electric charges according to incident electromagnetic waves,so that the active element array can read out the produced electriccharges; and

a protection member (surface protection film 36) provided on thesubstrate to cover the semiconductor layer (X-ray conductive layer 12),

wherein

the protection member is preferably made of a material that can befabricated below a heat resistant temperature of the semiconductorlayer.

If the semiconductor layer is made of an a-Se film for example, thecrystallization of the semiconductor layer is prompted at relatively lowtemperatures of 60° C. to 80° C. (heat resistant temperature). Such asemiconductor layer deteriorates in terms of photoelectric conversioncharacteristics when heated above the heat resistant temperature.According to the arrangement, the protection member is composed of amaterial (for example, silicone resin) that can be fabricated below theheat resistant temperature of the semiconductor layer; therefore, thedeterioration of the characteristics of the semiconductor layer isavoidable.

Furthermore, the two-dimensional image detector is preferably such thatthe protection member includes:

a surface protection film 36 composed of a resin;

a solid substrate (protection glass plate 35 a) covering the surfaceprotection film 36; and

a connecting member (sealant 35 b) for securing the solid substrate tothe substrate (the structure is shown in FIG. 16).

According to the arrangement, the semiconductor layer is given doubleprotection. This provides better protection to the semiconductor layer.

In the present invention, the surface protection member 35 and thesurface protection film 36 are employed for the purpose of achievingboth the object in the manufacturing process of the two-dimensionalimage detector and the object after the completion of thetwo-dimensional image detector. By contrast, if only the latter objectneeds to be achieved, the two-dimensional image detector may bemanufactured by other methods than those discussed in the foregoing. Ifa two-dimensional image detector is manufactured by other methods thanthe present invention, however, with the same structure upon completionas the present invention, it will have the same advantages as thetwo-dimensional image detector in accordance with the present invention.

As detailed so far, a manufacturing method for a two-dimensional imagedetector in accordance with the present invention is a manufacturingmethod for a two-dimensional image detector including:

a semiconductor layer for producing electric charges according toincident electromagnetic waves; and

a substrate having an active element array for reading out the electriccharges produced by the semiconductor layer,

the manufacturing method preferably including the steps of:

(1) forming the active element array on the substrate;

(2) forming a protection member on the substrate so as to cover an areain which the active element array is formed;

(3) dividing into smaller pieces the substrate on which the protectionmember is already formed;

(4) removing the protection member from the divided pieces; and

(5) forming the semiconductor layer on the active element array wherethe protection member is removed.

A manufacturing method for a two-dimensional image detector inaccordance with the present invention incorporates all the features ofthe foregoing manufacturing method for a two-dimensional image detector,and preferably further includes the step of mounting a circuit componenton the substrate, the circuit component being connected to the activeelement array, after the division of the substrate and before theremoval of the protection member.

According to the method, an active element array is formed on asubstrate, and then a protection member is formed on the active elementarray. Subsequently, the substrate is divided. Further, with theprotection member still remaining in place, a circuit component forconnecting to the active element array is mounted on the substrate.After removing the protection member, a semiconductor layer is formed ona surface of the active element array which was protected by theprotection member.

When circuit components are mounted on the substrate, gases and dust maybe produced in some cases that pollute the active element array and thesemiconductor layer. The pollutants, if having contacted the activeelement array and the semiconductor layer, would invite deterioration ofperformance by the active element array and the semiconductor layer.

However, in the foregoing method, the active element array is protectedby the protection member during the mounting of the circuit components,as well as during the division of the substrate. Further, thesemiconductor layer is formed after the mounting of circuit components.Therefore, the active element array and the semiconductor layer areprevented from contacting pollutants produced in mounting. Thus, theperformance of the active element array and the semiconductor layer isbetter, protected from deterioration, and the reliability thereofimproves.

As a result, the performance of the active element array and thesemiconductor layer can be better maintained at a satisfactory level,and two-dimensional image detector can be manufactured with higherreliability.

A manufacturing method for a two-dimensional image detector inaccordance with the present invention incorporates all the features ofthe foregoing manufacturing method for a two-dimensional image detector,and is preferably such that the protection member is made of aphotosensitive resin.

Scribe technologies are a preferred method of dividing the substrate,because it involves a simple device and exhibits excellent operationalperformance. If there is a protection member or the like covering partsof the substrate where the substrate is divided, it obstructs theformation of scribe lines. Accordingly, to use a scribe technology, thesubstrate needs to be exposed where it is divided.

In the foregoing method, the protection member is composed of aphotosensitive resin, and therefore can be readily patterned by means ofcoating, exposure, development, as in, for example, photolithography.Thus, the protection member can be patterned so as to cover where theactive element array is formed on the substrate and removed from partsof the substrate where it will be later divided. Scribe technologies arethus available.

As a result, it becomes possible to manufacture two-dimensional imagedetectors by a relatively simple steps with higher reliability.

Alternatively, a manufacturing method for a two-dimensional imagedetector in accordance win the present invention incorporates all thefeatures of the foregoing manufacturing method for a two-dimensionalimage detector, and is preferably such that the protection member ismade of an aqueous resin.

In the foregoing method, the projection member is composed of an aqueousresin, and therefore can be removed by the use of water or warm water ina later step of removing the protection member. The steps of removingthe protection member therefore does not need a special device, allowingfor a relatively simple configuration of the production line. Further,since no special solvent is not needed to remove the protection member,it becomes possible to reduce negative effects of the use of solvents onthe active element array and the components disposed on the substrate,as well as negative effects of the manufacture of two-dimensional imagedetectors on the environment.

As a result, it becomes possible to manufacture two-dimensional imagedetectors by simple, environment-friendly steps with higher reliability.

A manufacturing method for a two-dimensional image detector inaccordance with the present invention is a manufacturing method for atwo-dimensional image detector including:

a semiconductor layer for producing electric charges according toincident electromagnetic waves; and

a substrate having an active element array for reading out the electriccharges produced by the semiconductor layer,

the manufacturing method preferably including the steps of:

(1) forming the active element array on the substrate;

(2) forming the semiconductor layer on the active element array;

(3) forming a protection member on the substrate so as to cover an areain which the semiconductor layer is formed; and

(4) dividing the substrate on which the protection member is alreadyformed.

A two-dimensional image detector in accordance with the presentinvention preferably includes:

a substrate;

an active element array provided on the substrate;

a semiconductor layer, provided on the active element array, forproducing electric charges according to incident electromagnetic wavesso that the electric charges are read out by the active element array;and

a protection member, provided on the substrate, for covering thesemiconductor layer.

A two-dimensional image detector in accordance with the presentinvention incorporates all the features of the foregoing two-dimensionalimage detector, and is preferably such that the protection member ishermetic.

According to the arrangement, the protection member is capable ofmaintaining the hermetical sealing of the semiconductor layer fromambient air. Therefore, dew drops and other phenomena can be preventedfrom developing due to the environment in which the two-dimensionalimage detector is used, more effectively preventing deterioration inperformance of the active element array and the semiconductor layer.Thus, the two-dimensional image detector becomes more reliable.

Alternatively, a two-dimensional image detector in accordance with thepresent invention incorporates all the features of the foregoingtwo-dimensional image detector, and preferably such that a gap betweenthe semiconductor layer and the protection member is filled with anelectrically insulating substance.

According to the arrangement, by filling up the gap between thesemiconductor layer and the protection member with an electricallyinsulating substance, electric discharge is prevented from happeningaround the semiconductor layer even when a high voltage is applied tothe semiconductor layer during the use of the two-dimensional imagedetector. This prevents the deterioration in performance of thesemiconductor layer due to electric discharge, in addition to theaforementioned pollution of the active matrix element and thesemiconductor layer. Thus, it becomes possible to offer two-dimensionalimage detectors with even higher reliability.

Alternatively, a two-dimensional image detector in accordance with thepresent invention incorporates all the features of the foregoingtwo-dimensional image detector, and preferably such that a gap betweenthe semiconductor layer and the protection member is filled with aconductive member.

According to the arrangement, by filling up the gap between thesemiconductor layer and the protection member with a conductive member,the area can be maintained equal in terms of electric potential. Thisalso prevents electric discharge from happening around the semiconductorlayer.

Furthermore, according to the arrangement, electricity needs to besupplied to the conductive member to apply an electric field to thesemiconductor layer, which offers a wider ranges of choices on whereelectricity is to be applied. It thus becomes possible to prevent leadsfrom overlapping an area at which the image is read and casting a shadowin the produced image causing deterioration in image quality.

As a result, two-dimensional image detectors can be manufactured withhigh reliability and satisfactory image quality.

A two-dimensional image detector in accordance with the presentinvention incorporates all the features of the foregoing two-dimensionalimage detector, and preferably such that a portion of the protectionmember oppositely facing the semiconductor layer is constituted by asolid substrate.

According to the arrangement, the solid substrate may be composed of,for example, a glass substrate, a resin sheet, or other solid materialscontaining no solvents and the like that act as pollutants to thesemiconductor layer. Therefore, even if the protection member contactsthe semiconductor layer, the semiconductor layer can be prevented frombecoming polluted.

A two-dimensional image detector in accordance with the presentinvention incorporates all the features of the foregoing two-dimensionalimage detector, and preferably such that the protection member includes:

a surface protection film composed of a resin;

a solid substrate covering the surface protection film; and

a connecting member for securing the solid substrate to the substrate.

According to the arrangement, the semiconductor layer is given doubleprotection. This provides better protection to the semiconductor layer.

A two-dimensional image detector in accordance with the presentinvention preferably includes:

a substrate;

an active element array provided on the substrate;

a semiconductor layer, provided on the active element array, forproducing electric charges according to incident electromagnetic wavesso that the electric charges are read out by the active element array;

a surface electrode layer, provided on the semiconductor layer, forallowing a bias voltage to be applied to the semiconductor layer; and

a protection member, provided on the substrate, for covering thesemiconductor layer and the surface electrode layer.

A two-dimensional image detector in accordance with the presentinvention incorporates all the features of the foregoing two-dimensionalimage detector, and is preferably such that the protection member iscomposed of a resin material formed by coating or transfer.

According to the arrangement, the protection member is formed of acoating-type resin material that can be readily fabricated by coating bythe use of a spray or print technology or transfer by the use of anadhesive agent; therefore, the protection member can be readilyfabricated.

Further, if the resin material can be deposited at relatively lowtemperatures, even when a-Se with a low heat resistant temperature isused for the semiconductor layer in the two-dimensional image detector,the protection member can be formed without degrading photoelectricconversion characteristics of the a-Se.

A two-dimensional image detector in accordance with the presentinvention incorporates all the features of the foregoing two-dimensionalimage detector, and is preferably such that the protection member isconstituted by a solid substrate that is already in a solid state whenattached to the substrate.

According to the arrangement, the solid substrate, which is already in asolid state when attached to the substrate, does not contain solvents,ions, or other pollutants that pollute the semiconductor layer.Therefore, even if the protection member contacts the semiconductorlayer or the surface electrode layer when attached to the substrate, thesemiconductor layer and the surface electrode layer are prevented frombecoming polluted.

A two-dimensional image detector in accordance with the presentinvention incorporates all the features of the foregoing two-dimensionalimage detector, and is preferably such that the protection memberincludes:

a solid substrate that is already in a solid state when attached to thesubstrate; and

a connecting member for securing the solid substrate to the substrate.

According to the arrangement, the protection member includes: a solidsubstrate that is already in a solid state when attached to thesubstrate; and a connecting member for securing the solid substrate tothe substrate. Under these conditions, by disposing the connectingmember along the periphery of the solid substrate so as to frame thesolid substrate for example, the connecting member and the solidsubstrate can keep the semiconductor layer and the surface electrodelayer hermetically sealed from ambient air. Therefore, pollutants anddew drops are prevented from being produced during the use of thetwo-dimensional image detector. This effectively prevents thedeterioration in the performance of the active element array, thesemiconductor layer, and the surface electrode layer, and enablestwo-dimensional image detectors to be manufactured with even higherreliability.

A two-dimensional image detector in accordance with the presentinvention incorporates all the features of the foregoing two-dimensionalimage detector, and is preferably such that the solid substrate is aceramic substrate.

According to the arrangement, the solid substrate constituted by aceramic substrate, if disposed to the substrate on which the activeelement array is formed, can impart an extra strength to the substrate.

A two-dimensional image detector in accordance with the presentinvention incorporates all the features of the foregoing two-dimensionalimage detector, and is preferably such that the ceramic substrate is aglass substrate.

Since the ceramic substrate (solid substrate) is made of glass, if thesubstrate on which the active element array is formed is constituted bya glass substrate, the two substrates have identical coefficients ofthermal expansion. This arrangement prevents the substrates from warpingdue to a difference in their coefficients of thermal expansion, even ifthe substrate on which the active element array is formed and the solidsubstrate (protection member) are both secured.

A two-dimensional image detector in accordance with the presentinvention incorporates all the features of the foregoing two-dimensionalimage detector, and is preferably such that the ceramic substrate iscomposed of one of the materials consisting of aluminum oxide, aluminumnitride, boron nitride, silicon oxide, and silicon carbide.

The ceramic substrate (solid substrate), when composed of one of thematerials consisting of aluminum oxide, aluminum nitride, boron nitride,silicon oxide, and silicon carbide, absorbs a reduced amount of X-raysin comparison to the ceramic substrate composed of glass; therefore theuse of the ceramic substrate can prevent a significant drop in thesensitivity of the two-dimensional image detector.

A two-dimensional image detector in accordance with the presentinvention incorporates all the features of the foregoing two-dimensionalimage detector, and is preferably such that the ceramic substrate iscomposed of a mixture of two or more of the materials constituting ofaluminum oxide, aluminum nitride, boron nitride, silicon oxide, andsilicon carbide at an arbitrary ratio.

If tow or more of the ceramic materials are mixed at an arbitrary ratioto obtain the solid substrate, the coefficient of thermal expansion canbe arbitrarily specified by changing the mixture ratio. This enables theceramic substrate formed to have substantially the same coefficient ofthermal expansion as the substrate on which the active element array isformed, and thus ensures the prevention of the substrates from warpingdue to a difference in the coefficients of thermal expansion.

A two-dimensional image detector in accordance with the presentinvention incorporates all the features of the foregoing two-dimensionalimage detector, and is preferably such that the solid substrate is aresin substrate.

According to the arrangement, the solid substrate constituted by a resinsubstrate, if disposed to the substrate on which the active elementarray is formed, can impart an extra strength to the substrate. Further,a resin substrate can be readily fabricated, allowing for easy formationof, for example, a through hole and notch therein. This ensures theapplication of a bias voltage to the surface electrode layer through thethrough hole or notch. Besides, the resin substrate is relative light inweight in comparison to glass and other ceramic substrates, whichcontributes to a reduction in the weight of the two-dimensional imagedetector.

A two-dimensional image detector in accordance with the presentinvention incorporates all the features of the foregoing two-dimensionalimage detector, and is preferably such that the resin substrate iscomposed of a resin containing no Si element.

According to the arrangement, the use of a resin substrate with no Sielement reduces the absorption of X-rays by the solid substrate incomparison to Si-containing glass or ceramic substrates. This ensuresthe prevention of a drop in the sensitivity of the two-dimensional imagedetector caused by the provision of the solid substrate.

A two-dimensional image detector in accordance with the presentinvention incorporates all the features of the foregoing two-dimensionalimage detector, and is preferably such that a gap between thesemiconductor layer and the protection member is filled with anelectrically insulating substance.

According to the arrangement, by filling up the gap between thesemiconductor layer and the protection member with an electricallyinsulating substance, electric discharge is prevented from happeningaround the semiconductor layer and the surface electrode layer even whena high voltage is applied to the semiconductor layer via the surfaceelectrode layer during the use of the two-dimensional image detector.This ensures the protection of components from destruction due toelectric discharge and the prevention of the deterioration inperformance of the semiconductor layer and the surface electrode layerdue to electric discharge, in addition to the prevention of theaforementioned pollution and formation of dew drops in the active matrixelement, the semiconductor layer, and the surface electrode layer.

A two-dimensional image detector in accordance wist the presentinvention incorporates all the features of the foregoing two-dimensionalimage detector, and is preferably such that a gap between thesemiconductor layer and the protection member is filled with aconductive member.

According to the arrangement, by filling up the gap between thesemiconductor layer and the protection member with a conductive member,the area can be maintained equal in terms of electric potential.Therefore, electric discharge is prevented from happening around thesemiconductor layer and the surface electrode layer even when a highvoltage is applied to the semiconductor layer via the surface electrodelayer. This ensures the protection of components from destruction due toelectric discharge and the prevention of the deterioration inperformance of the semiconductor layer and the surface electrode layerdue to electric discharge, in addition to the prevention of theaforementioned pollution and formation of dew dross in the active matrixelement, the semiconductor layer, and the surface electrode layer.

Furthermore, according to the arrangement, electricity needs to besupplied to the conductive member to apply an electric field to thesemiconductor layer, which offers a wider ranges of choices on whereelectricity is to be applied. It thus becomes possible to prevent leadsfrom overlapping an area at which the image is read and casting a shadowin the produced image causing deterioration in image quality.

A two-dimensional image detector in accordance with the presentinvention incorporates all the features of the foregoing two-dimensionalimage detector, and is preferably such that a metal film is formed on asurface of the protection member opposite to a surface thereof facingthe semiconductor layer.

According to the arrangement, by forcing a metal film on a surface ofthe protection member opposite to a surface thereof facing thesemiconductor layer, enhanced electrical shield and light obstruction isimparted to the two-dimensional image detector. The buildup of staticelectricity is also preventable.

A two-dimensional image detector in accordance with the presentinvention incorporates all the features of the foregoing two-dimensionalimage detector, and is preferably such that the protection member isprovided with a through hole or a notch through which a bias voltage isapplied to the surface electrode layer.

According to the arrangement, the protection member is provided with athrough hole or a notch; therefore, a bias voltage can be readilyapplied to the surface electrode layer through the through hole or thenotch with the protection member being already provided on thesubstrate. The through hole and the notch may be disposed along theperiphery of the protection member, for example.

A two-dimensional image detector in accordance with the presentinvention incorporates all the features of the foregoing two-dimensionalimage detector, and is preferably such that the surface electrode layeris provided with a surface electrode pull-out holder through which abias voltage is applied to the surface electrode layer so that itpartially extends external to the protection member.

According to the arrangement, the surface electrode layer is providedwith a surface electrode pull-out holder partially extending external tothe protection member; therefore, a bias voltage can be readily appliedto the surface electrode layer through the surface electrode pull-outholder with the protection member being already provided on thesubstrate.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art intended tobe included within the scope of the following claims.

What is claimed is:
 1. A method of manufacturing a two-dimensional imagedetector including: a semiconductor layer for producing electric chargesaccording to incident electromagnetic waves; and a substrate having anactive element array for reading out the electric charges produced bythe semiconductor layer, the manufacturing method comprising the stepsof: (1) forming the active element array on the substrate; (2) formingthe semiconductor layer on the active element array; (3) forming aprotection member on the substrate so as to cover an area in which thesemiconductor layer is formed, without covering areas near predetermineddividing lines of the substrate; and (4) dividing the substrate, alongthe predetermined dividing lines, on which the protection member isalready formed.
 2. The method of manufacturing a two-dimensional imagedetector as defined in claim 1, wherein in the step (3), the protectionmember is constituted by a solid substrate and a connecting member, andthe solid substrate is secured to the substrate using the connectingmember after forming the connecting member at a circumference of thesemiconductor layer in the substrate.
 3. The method of manufacturing atwo-dimensional image detector as defined in claim 2, further comprisingthe step of filling up a space surrounded by the solid substrate and thesubstrate with an electrically insulating substance.
 4. The method ofmanufacturing a two-dimensional image detector as defined in claim 2,further comprising the step of forming a metal film on a surface of thesolid substrate opposite to a surface thereof facing the semiconductorlayer.
 5. A method of manufacturing a two-dimensional image detectorincluding: a semiconductor layer for producing electric chargesaccording to incident electromagnetic waves; and a substrate having anactive element array for reading out the electric charges produced bythe semiconductor layer, the manufacturing method comprising the stepsof: (1) forming the active element array on the substrate; (2) formingthe semiconductor layer so as to cover the active element array; (3)forming on the semiconductor layer a surface electrode layer throughwhich a bias voltage is applied to the semiconductor layer; (4) forminga protection member on the substrate so as to cover the semiconductorlayer and the surface electrode layer, without covering areas nearpredetermined dividing lines of the substrate; and (5) dividing intosmaller pieces the substrate, along the predetermined dividing lines, onwhich the protection member is already formed.
 6. The method ofmanufacturing a two-dimensional image detector as defined in claim 5,wherein in the step (4), the protection member is constituted by a solidsubstrate and a connecting member, and the solid substrate is secured tothe substrate using the connecting member after forming the connectingmember at a circumference of the semiconductor layer in the substrate.7. The method of manufacturing a two-dimensional image detector asdefined in claim 6, further comprising the step of filling up a spacesurrounded by the solid substrate and the substrate with an electricallyinsulating substance.
 8. The method of manufacturing a two-dimensionalimage detector as defined in claim 6, wherein a conductive layer isformed on one of two surfaces of the secured substrate, and the securedsubstrate is secured to the substrate using the connecting member so asto sandwich a conductive material between the conductive layer and thesurface electrode layer.
 9. The method of manufacture a two-dimensionalimage detector as defined in claim 8, wherein the conductive layer isformed on the secured substrate so as to oppositely face, and extendbeyond, the surface electrode layer.
 10. The method of manufacturing atwo-dimensional image detector as defined in claim 6, further comprisingthe step of forming a metal film on a surface of the solid substrateopposite to a surface thereof facing the semiconductor layer.
 11. Amethod of manufacturing a two-dimensional image detector as recited inclaim 1 wherein all of the predetermined dividing lines are provided soas to be exposed.
 12. A method of manufacturing a two-dimensional imagedetector as recited in claim 5 wherein all of the predetermined dividinglines are provided so as to be exposed.